10.1 Driving Capacitive Load

Capacitive Loads decrease the phase margin of all op amps. The output impedance of a feedback amplifier becomes inductive at high frequencies, creating a resonant circuit when the load is capacitive. This can lead to overshoot, ringing and oscillation. To eliminate oscillation or reduce ringing, an isolation resistor can be placed between the load and the output. In general, the bigger the isolation resistor, the more damped the pulse response becomes. For initial evaluation, a 50 Ω isolation resistor is recommended.